The present invention relates to a method and device for controlling data transmission.
Personal computers and peripheral equipment, such as a digital video camera and a color printer, are provided with serial interfaces that comply with the IEEE 1394 standard. Data transmitted in a network system includes information of the nodes transmitting and receiving the data. Every node in the network system is provided with a repeat-transmit function, which transfers the received data. Each node is also provided with a feed function for providing the received data to a device having a higher rank than the interface (e.g., CPU) in the same node when the received data is addressed to that node. The repeat-transmit and feed functions transmit data to every device in the network system. Further, the repeat-transmit and feed functions further transmit data between certain devices.
When data is transmitted between two nodes, the data (first data) is transmitted to every node connected to the network system, even if the two nodes are located adjacent to each other. Therefore, nodes irrelevant to the data transmission between the two nodes (nodes excluding the transmitting node, the receiving node, and intermediate nodes located between the transmitting and receiving nodes) are not allowed to transmit data (second data) until the data transmission between the two nodes is completed. In this case, a request for transmitting the second data is generated again after the transmission of the first data is completed.
Nodes and lines configure a network topology, or a network system. In the prior art, data packets, which are transmitted between certain nodes, occupy the network system. Thus, as the number of data packets transmitted at the same time increases, the amount of data that can be transferred during a certain period decreases. This decrease the transfer efficiency, or the virtual transfer speed, of the data packets.